Incursion
Part of speech: noun
Definition: An aggressive movement into somewhere; an invasion.
Invasion
Part of speech: noun
Definition: A military action consisting of armed forces of one geopolitical entity entering territory controlled by another such entity, generally with the objective of conquering territory or altering the established government.
Example sentence: I grew up believing my sister was from the planet Neptune and had been sent down to Earth to kill me. I believed this because my sister Emily convinced me of it when I was a toddler. I think she'd seen Invasion of the Body Snatchers and her imagination ran away with her. There's a part of me that still believes it.